The conventional portable telephones are each constituted to allow the setting for a vibrator to be driven at an incoming call mode in order to notify an incoming call by causing vibration other than a melody and the like. Generally, this vibrator has a DC motor in which a weight is attached in a deflected manner to a rotation shaft of a rotor; therefore, by driving it to rotate, vibration is generated.
By the way, the aforementioned portable telephones can be each set to notify users with incoming calls with both sound and vibration by driving the vibrator simultaneously with generation of the melody and the like.
However, the sound such as the melody of the musical tune does not have correlation to the vibration; therefore, when the conventional telephone is used with the setting for allowing incoming call notification by simultaneously generating sound and vibration, there is a problem in that the user of the portable telephone may have a feeling of wrongness.
As a vibration source, a vibration speaker having a vibration function is known. The vibration speaker is set such that the resonance frequency of the cone side differs from the resonance frequency of the magnet side; therefore, it is constituted such that the sound output and the vibration are generated in different frequency bands respectively. In the conventional portable telephones, vibration speakers have not been known as constituent elements for realizing vibration functions. This is because in order to reliably generate vibration using a vibration speaker, it is necessary to control the frequency characteristic of the drive system of the vibration speaker to follow up with variations of the resonance frequency of the magnet side of the vibration speaker causing the vibration. For this reason, there is a problem that the circuit configuration should be complicated.
The present invention is made in consideration of the aforementioned circumstances; and it is a first object to provide a vibration source driving device, as a means for realizing a vibration function on the portable telephone and the like, in which at an incoming call mode when both sound and vibration are simultaneously generated to perform incoming call notification, a correlation is introduced between the vibration and the sound corresponding to the melody of the musical tune, so that the user is able to enjoy it without having a feeling of wrongness.
In addition, it is a second object of the present invention to provide a vibration source driving device, as a means for realizing a vibration function on the portable telephone and the like, in which a vibration speaker used as a vibration source can be driven without using the complicated circuit configuration.